Since the dawn of the computer age one of the most steady and continuous trends has been toward miniaturization. This trend manifests itself in every facet of the industry. Cell phones, personal digital assistants (PDAs), portable computers etc. have all decreased in size at astounding rates. Conversely, however, as these devices have shrunk they have also become more powerful. This dichotomy is somewhat problematic. The need to communicate information to, and glean information from, a user increases commensurately with the power of a device, while the real estate available for these display and data entry interfaces naturally shrinks along with the device.
With each of the two subsystems of data entry and display, there are inherent physical limitations on possible size reduction before each subsystem becomes either ineffective or useless. The physical limitations placed on communications to a user are much greater than those placed on an interface for data entry. These limitations may include hardware limitations, physiological limitations, and the fact that, in most cases, data must be communicated to a user visually. Therefore, the majority of a device's footprint reserved for communications and data entry may be taken up by a visual display. This visual display leaves little room for an interface for data entry.
Solutions to address this problem have been devised by incorporating handwriting software in a device. To utilize this solution, a user may directly enter text by writing on a touch sensitive display. This handwritten data is then converted by handwriting recognition software into digital data. While this solution allows one display to both communicate information to, and receive data from, a user, the accuracy and speed of handwriting recognition software is notoriously bad. Additionally, printing or writing with a stylus is generally slower than typing, or key based input, and requires the use of two hands.
It is therefore advantageous to use an interface for entering data which is small and may be operated with one hand. Prior attempts at such a keyboard have resulted in the development of a keyboard that has a reduced number of keys. FIG. 1 shows a prior art reduced keypad 100 for a device. The keypad 100 is a standard telephone keypad having ten number keys 110-128 an asterisk (*) key 130, and a pound (#) key 140. For English, and many other alphabet languages, the numeric keypad of the telephone is overlaid with an alphabet keypad where three letters are associated with each number key 110-128. For example, the two (2) key 114 is associated with the letters a-b-c. With some of these reduced key devices, a user may employ multiple key presses to enter words or names.
However, this solution is problematic as well, as Chinese and other character based languages such as Japanese kanji do not have a manageable number of letters which can be overlaid onto a numeric keypad. An additional problem is that each key press may contain multiple characters, creating ambiguity in a sequence of keystrokes.
A solution to the problem of ambiguity is to have the user enter two or more keystrokes to specify each letter, the keystrokes may be entered simultaneously (chording) or in sequence. However, these approaches require many keystrokes and are consequently inefficient. Ideally, a data entry method would require one keystroke per letter.
In the past, word level disambiguation has been used to disambiguate entire words by comparing the sequence of received keystrokes with possible matches in a dictionary. But, because of decoding limitations, word level disambiguation does not give error free decoding of unconstrained data with an efficiency of one keystroke per character.
Thus, there is a need for apparatuses, methods and systems for interfaces which enable the efficient one-handed entry of a variety of data, and the ability to reduce the number of strokes required for data entry by using logic for the resolution of character ambiguity and the predictive completion of input.